The end product of a dry flue gas desulfurization process is a dry bulk solid composed of relatively fine particle sizes. This bulk solid includes compounds from both the combustion process which generated the flue gas and reaction products from the desulfurization process. Typical constituents of this bulk solid consist of flyash, sulfur based reaction products (such as calcium sulfite and calcium sulfate compounds), un-used reagent (such as excess lime), and relatively inert compounds that were present in the fresh reagent supply.
In some cases, the bulk solid was disposed of in the best manner possible, such as in a landfill. In other cases, attempts were made to retrieve some or all of the un-used reagents or other compounds for recycling or for further utilization with the remainder then being disposed of. These methods of recycling employed make-up water or other liquid so as to separate the desired component from the bulk solid. However, no attempt was made to classify or categorize this bulk solid into its component parts using dry classifiers so that further uses could be found thereby recycling a greater percentage of the bulk solid and/or reducing or eliminating the need for further landfilling. As contemplated by this invention, a dry classification scheme would be implemented which utilizes air as the motive fluid in conjunction with or assisted by mechanical action so as to classify the bulk solids into a fine and a coarse solids stream.
Additionally, in the past, when such portions were removed from the flue gas desulfurization end product stream, the particle size of the portion removed was not consistent. This was due, for example, to some of the to-be-recycled lime being agglomerated into larger particles, or conversely, to the desired fines being contained within the larger particles and thus not being collected. In accordance with this invention, the larger end product particles may, if such is desired, be reduced in size by comminution which also liberates the fines such larger particles contain. In this fashion, a greater portion of the desired end product is available for subsequent separation and classification.
It is thus an object of this invention to separate the end product of a flue gas desulfurization process into its component parts using a dry classification scheme. Another object of this invention is to achieve classification so that like components may be gathered and collected together for further use or implementation. Still another object of this invention is to classify the bulk solids by size which, in turn, will result in the desirable classification by content due to the variations in particle density between the different components of the bulk solid. Yet another object of this invention is to remove and dispose of only that portion of the bulk solid which is in need of being landfilled with the remaining portion of the bulk solid being delivered elsewhere for subsequent utilization. These and other objects and advantages of this invention will become obvious upon further investigation.